And manchester



(N0 Model.)

A. H. HOYT.

GALVANOMETBR.

' No. 532,560. Patented Jan. 15, 1895.

UNITED STATES PATENT OFFICE.

- ADRIAN H. IIOYT, OF PENACOOK, NEW HAMPSHIRE, ASSIGNOR T0 THE WHITNEY ELEOTRIOAL INSTRUMENT OOMPANY, OB SACO; MAINE,

AND MANCHESTER, NEW HAMPSHIRE.

GLVANOMETER.

SPEGIFIGATION forrm'ng pa rt of Letters Patent N0. 532,560, dated J'a'nuary 15, 1895.

Applioation filed April 2l 3 18 94- Serial N0. 508,931. (N0 model.)

5 in Galvanometers,of which the following description, in connection with the aocompany- 1ng drawings, is a speoification, like letters on the drawings representing likeparts.

My invention relates to electrioal iI1dicat- May 16.1893, I have shown and desoribedanindicating instrument whiebmay be employed in carrying out the present invention, said invention consisting in certain improvements applicable to the instrument shown in said former patent among others. I have therefore shown in the appended drawings forming part of this speoifieation a devi0e the main portion of whioh is substantially the same as that shown in Said prior Patent N0. 497,449, but I do not wish to be understood as limiting my present invention to an instrument of exa ctly this desoription, sinoe the novel features thereof might be applied to various instrnrnents in whioh the movement of anarmature er needle linder the inductive influenoe of an eleotrie current is used to indicate the qn antity or potential thereof.

In earrying out my invention I prefer to employ a eoil or solenoid of insulated. wire of sufifioiently high eonductivity to oarry electric ourrents of the character for whioh the 5 instrument is designed, and almovable core piece or arrnatnre in inductive proximity thereto, so that the eurrent flowing in the coil will cansethe said. armature to move, the extent of said rinovement in opposition 120 an opposing foree indicating the amount of the eurrent. In order that the amount of eurrent ing instruments, such as galvanometersand .thus indioat-ed may be observed, I employ a pointer aotuated by said armature,and a soale upon the face of the instrument traversed by the said pointer as is usual in instruments of this description. In calibrating the soale,

however, it is found that the inerements of movernent 0f the arrnature are not directly proportional tothe inorements of currenti ployed. For example, in an instrument having a range'from 0 where no ourrent 1s indicated, to 150, indioating a current 0f one hundred and fifty volts, the graduations are exceedingly small at the beginning of tl1e seale, inereasing as they approach the middle and again decreasing toward the end.

My present invention embodies oertain improvements in the arrangementof the instrument, whereby this variable ratio between the increments of onrrent-strength and armature movement ma y to a oertain extent be compensated for, and the graduations on the scale made more neariy uniform. I have found that this may be aeoonriplished to sorne extent by confining ehe movement of the armature withinoertain limits, that is to say, rendering it movable only through that portion of its path in whioh its inorements of movement vary the least with relation to the incre ments of current-strength. In order to avoid unneoessarily enlarging tl1e instrument as would be neoessary t0 Obtain a legibie seale if the pointer were direotly connected to the arniaturennder these conditions, I mount the indioator or pointer independently, and employamultiplying eonneoti0n between the two, such conneotion being also so arranged as 130 have a meohanieal compensating efiect at the pointer for the variation in inoren1ent s not wholly obviated by the decreased movement of the armature, as will be sl1own hereinafter.

In the aoeompanying drawings, Figure 1 is plan view of the instrument. Figs. 2 and 3 are details the former being somewhat en- ICI) largecl, and Fig. 4 is a cross-section ef Fig. 2, on ehe line x, 0c, looking from the right.

Referring to Figs. 1 and 2, the coil a is wound upon a hollow 01 tnbular supporting shell a preferably fiattened in cross-section so as to form a narrow opening within the coil, as best shown in Fig. 4. The Said Shell is provided with flanges a adapted to retain the coi1 in plane, and also forming a support; for brackets a between which are pivotally supported the armature b and frhe pointer c upon spindles b and o respectively, arranged parallel t0 each other. A rheostat R in series with the coil a (the eircuit connections nob being shown) provided with a calibrat d scale R is placecl in any convenient part of the instrnment, tl1e Operation of whieh will be hereinafter more fully described. The movable member or armature b of the device cousists 0f a Hat, 'fan-shaped piece 0f metal such as soft-iron eapable of being magnetized er demagnetized by the induetive eifeet of a eurreni; of electrieity in proximity thereto. The saicl armature is mounted near one end on a spindle b snpported in bearings a upon the brackets a and the said bearings are so situated with relatlon to the c0il thab substantially the entire armature extends 011iward therefrom over the narrow opening thereof, its lower half normally extending downward into said opening, thus being under the influence of the magnetic Held developed by a current flowing throngh ehe coi1. I fnrther provide an arm 12 extending outwardly in line with the armature beyond its pivotal bearing, and a counterpoise b carried upon said arm and preferably adj ustable with relation thereto, the object of said counterpoise being 130 balanee the weight oi: the armature.

Snitable stops b (Figs. 2 and 4) secnred to the base of tl1e instrument in the patl1 of the arm 12 limit the movement of the armature, said stops being so situated that the armature moves in that portion of the field Where the incrernents of current-strength are most nearly related to the inc rements of movement 0f a body indnc-tively infiuenced thereby.

A pointer c mounted 011 a spindle c pivoted in bearings ab 0 npon the sanne brackets a which support the armature bearings a is arranged t0 move over the seale 0 between tl1e stops 0 (Fig. l). The said pointeris provided with a counterpoise 0 best shown in Fig. 2, whereby it is balanced in its bearings. The said pointer is connected t0 the armature by means of a link b Which may be a wire er thread fastened to the arnnature near the free end thereof, said link extending t0 an arm er projection 0 radial to the spindle c and suitably fastened thereto 0r integral therewith. As tl1e armature moves into the magnetic field under tl1e influence of the eurrent, its movementis commnnicated throngh the link 12 to the arm c thus tnrning the spindle c in its bearings to the right and carrying tl1e pointer over the seal'e. The pointer c tl1ns forms the long arm 0i1 alever of which the bearings 0 ferne t-he fulcrum, while tl1e sl1ort arm is the perpendienlar distance between the saicl link band tl1e spindle c'- As the link moves the arm c to tl1e righi, it ob viously recedes from the axis thereof, thereby lengthening the short arm 015 the lever and deereasing the distance traveled by tl1e long arm er pointer With relation t0 that 0f the armature, and the instrument is so adjusted that; this con1-pensating eifect actsto eorrect the nnequal movement 0f the pointer which would resull: from a direct' connection with the armature. I am thus enablecl to bring the gradnations t0 an approximate equality, rendering the seale legible thronghoun its entire length, and the multiplying device admits of a comparatively short indicator moving in a comparacively long arc, thns materially redueing tl1e size of the instrnment.

lt is 110 be understood, of course, that tlie link 19 might be connected to ehe pointer itself 011 either side of its arbor, laut in this case the pointer in its initial position wonld extend outward from its arbor in the d-irection of the arm c necessitating a removal of the scale. By the use 0f the said arm c the pointer can be given any desired osition relative to its axis, so that the seale rnay be placed in the position m0st convenient forit.

The device as thus far described may be used on eircuits carrying e'ither a direct eurrent er an alternating current, sinee the armatnre b is normally non-polarized and capable of changing its polarity when influenced by the magnetic field, as the direetion 0f the enrrent changes. I1; is found however, that when an alternating current flows throngh the e0il a the movement of the armature with relation to the amount of enrreni; varies ac- IOO cordin g 1:0 the periodicity of the current, eince the self-induetion increases as the periodieity becornes higher. In Order t10 compensate for this change of relation I have provided means for putting more or lass resistance into the circuit; for eurrents of different periodieity. T0 this end, I employ a rheostatR shown diagrammatically in Fig. 3, the movable member of the said rheostat; being provided with acisuating means and a pointer traveling on a seale R, showing the condition 0f the rheostat. The scale R, is ealibrated to show the position in which the movable member of tl1e rheostat is 130 be placed for cnrrents of difierenn periodieity. The said rheostat; may be constrncted in any suitable manner, and I have shown it as comprising a movable member, consisting of a contact R carried by and radial to an arbor R having a knob er handle attached thereto for tnrning the said arm 130 various positions. A series 0f contacts R connected together throngh resistance coils R", is arranged in the path 0f the said movable arm so that as the said arm is turned, more or lese resistance is in- Gluded in the cireuit, tl1e arm being couneeted to one end of the circnio, while the IIO ' aeting upon a portion of the pointer such that the leverage incre2ises with the forward moVen1ent f the pointer, might beused. The said 1ink instead 0f being a wireor rod 100se1y 01 pivota.lly e'onnected with tharma.ture anti pointer respectively might; be a flexible couneetion as it i s subjected. t0 teh'sile strain only, and the arm 01 arms with which it is conneeted might have a cam snrfaee to produee'the eonnpensating effect. I prefer, however, to use the wire link shown sinee it is durable, simple, and efifeetual for the pnrpo3e desired.

I elaim 1. In an eleetriealindi'cating deviee, the combination with a. solenoid, and an armeture pivoted at one side of the end 0f said coil andextending outward from its pivot over the mouth of said coi1 and within the magnetic field. thereof, 01: an indicator er 0 pointer aetuated by said armature and a compensatin g c0nneetion between the free end of said. arrnat'ure and the seid pointer, as sei: forth.

2. The combination of the leetrieally 3 rnoved armatur;e er needle of an electrieal indicating device, and a pivbtally supported pointer or-indieator, with a link conneeted ab one end to seid eleetrieally moved armature and ab the other end to an arm eonneeted to 40' seid pointer, as set forth. 1 Y

3'. In an electarieal indiceting device, the eombination with a solenoid and movable armature in indnctive proximity thereto, of a rheostat in circuit with seid solenoid and a pointer conneeted. with seid rheostat rn0vab1e oxier a seale calibrated in terms of eurrent periodieity, as and for the purpose sei: forth.

In testimony whereof I ha.ve signed n1y nenne to this speeifieation in the pressence of two subscribing witnesses.

\ ADRIAN H. HOYT.

Witnesses:

J. ALBERT. MASSIE, HORACE D. BEAN. 

